Coaticook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Coaticook clear sky chart from 2005-11-06 to 2024-01-22.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	19% 12% 5% 8% 6% 3 5% 4 5% 6% 26%	74863
	Night	18% 13% 5% 9% 7% 3 5% 4 4 5% 26%	75076
Transparency	Day	59% 6% 10% 17% 8% 1	74568
	Night	62% 6% 9% 15% 7% 1	74905
Seeing	Day	28% 19% 28% 17% 7% 2	13635
	Night	27% 17% 26% 22% 8% 1	22638

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 18% 10% 14% 10% 5% 5% 5% 3 3 11%	1517
	11th to 20th	Day	15% 17% 8% 14% 9% 4 4 5% 3 5% 16%	1520
	21st to end	Day	10% 15% 8% 13% 10% 4 7% 5% 4 6% 19%	1592
February	1st to 10th	Day	15% 17% 8% 13% 11% 6% 6% 3 3 3 15%	1516
	11th to 20th	Day	12% 18% 10% 16% 9% 4 5% 4 4 4 15%	1748
	21st to end	Day	12% 17% 8% 12% 9% 5% 6% 4 4 4 19%	1480
March	1st to 10th	Day	13% 17% 7% 12% 8% 4 4 4 3 5% 22%	1797
	11th to 20th	Day	16% 14% 9% 9% 7% 3 4 3 4 4 28%	1872
	21st to end	Day	18% 18% 5% 10% 6% 3 4 3 3 4 27%	2333
April	1st to 10th	Day	21% 17% 6% 9% 4 2 4 4 3 5% 25%	2160
	11th to 20th	Day	19% 14% 4 5% 5% 3 4 3 3 5% 33%	2173
	21st to end	Day	24% 15% 4 6% 5% 3 4 4 4 6% 26%	2340
May	1st to 10th	Day	25% 11% 3 6% 5% 3 4 3 5% 6% 30%	2354
	11th to 20th	Day	21% 9% 4 6% 6% 3 5% 4 5% 6% 31%	2478
	21st to end	Day	19% 7% 3 6% 6% 4 5% 5% 6% 9% 29%	2725
June	1st to 10th	Day	28% 9% 3 5% 5% 3 5% 5% 5% 7% 25%	2520
	11th to 20th	Day	19% 7% 3 6% 5% 3 5% 5% 6% 8% 34%	2520
	21st to end	Day	23% 8% 3 6% 6% 3 5% 5% 6% 7% 27%	2520
July	1st to 10th	Day	19% 7% 2 5% 6% 2 5% 5% 7% 9% 33%	2520
	11th to 20th	Day	16% 7% 3 5% 5% 4 6% 6% 8% 9% 29%	2520
	21st to end	Day	19% 7% 2 7% 6% 4 6% 5% 6% 8% 29%	2744
August	1st to 10th	Day	18% 7% 3 6% 6% 4 6% 5% 6% 9% 30%	2471
	11th to 20th	Day	17% 6% 2 6% 6% 4 6% 6% 7% 9% 30%	2304
	21st to end	Day	20% 6% 3 4 5% 3 5% 6% 5% 8% 35%	2394
September	1st to 10th	Day	18% 7% 2 5% 4 3 5% 5% 4 7% 39%	2160
	11th to 20th	Day	20% 6% 3 5% 4 2 4 4 3 8% 42%	2012
	21st to end	Day	20% 8% 3 5% 4 3 4 5% 5% 9% 34%	1980
October	1st to 10th	Day	24% 11% 4 6% 4 2 5% 5% 6% 6% 28%	1972
	11th to 20th	Day	21% 13% 3 7% 6% 3 4 5% 6% 6% 27%	1688
	21st to end	Day	25% 21% 4 5% 5% 2 5% 3 3 4 22%	1782
November	1st to 10th	Day	20% 16% 5% 7% 6% 3 5% 3 4 5% 27%	1671
	11th to 20th	Day	18% 16% 7% 10% 7% 4 4 4 4 5% 22%	1710
	21st to end	Day	17% 17% 7% 10% 7% 4 5% 4 5% 6% 18%	1572
December	1st to 10th	Day	19% 21% 8% 14% 7% 3 3 3 3 4 15%	1520
	11th to 20th	Day	17% 17% 7% 12% 7% 4 5% 4 4 4 19%	1906
	21st to end	Day	22% 19% 6% 12% 8% 3 4 4 3 4 15%	2772
January	1st to 10th	Night	15% 21% 8% 15% 10% 4 6% 3 3 4 11%	2649
	11th to 20th	Night	15% 18% 8% 14% 11% 5% 6% 4 3 3 14%	2660
	21st to end	Night	10% 14% 8% 14% 12% 5% 7% 5% 3 3 19%	2798
February	1st to 10th	Night	13% 16% 8% 15% 11% 5% 6% 3 3 4 15%	2444
	11th to 20th	Night	11% 17% 7% 15% 10% 6% 6% 4 3 3 18%	2098
	21st to end	Night	14% 15% 8% 10% 10% 5% 6% 3 2 4 23%	1776
March	1st to 10th	Night	14% 18% 8% 10% 8% 3 5% 3 4 4 23%	2150
	11th to 20th	Night	17% 15% 7% 8% 6% 3 5% 4 3 5% 26%	2087
	21st to end	Night	18% 18% 6% 10% 4 3 4 3 3 4 29%	2021
April	1st to 10th	Night	21% 16% 5% 8% 7% 3 3 4 4 5% 25%	1800
	11th to 20th	Night	21% 13% 4 6% 6% 2 3 3 4 6% 32%	1736
	21st to end	Night	23% 13% 4 5% 6% 3 4 4 4 6% 28%	1620
May	1st to 10th	Night	23% 12% 4 6% 5% 4 3 5% 4 6% 30%	1620
	11th to 20th	Night	20% 8% 4 5% 6% 3 5% 5% 4 6% 34%	1415
	21st to end	Night	20% 6% 3 6% 6% 4 5% 4 5% 7% 34%	1550
June	1st to 10th	Night	27% 8% 3 5% 4 2 4 5% 5% 6% 30%	1440
	11th to 20th	Night	21% 5% 3 5% 4 3 4 6% 6% 7% 36%	1440
	21st to end	Night	20% 6% 4 6% 6% 3 6% 6% 5% 8% 31%	1440
July	1st to 10th	Night	16% 6% 3 6% 6% 3 5% 5% 6% 9% 36%	1440
	11th to 20th	Night	13% 6% 3 5% 5% 3 6% 6% 6% 11% 36%	1440
	21st to end	Night	15% 6% 3 6% 5% 3 6% 5% 6% 8% 36%	1574
August	1st to 10th	Night	18% 5% 2 4 5% 3 5% 6% 7% 9% 39%	1448
	11th to 20th	Night	16% 7% 3 7% 5% 3 5% 5% 6% 7% 37%	1596
	21st to end	Night	18% 6% 2 5% 6% 3 4 4 5% 7% 41%	1958
September	1st to 10th	Night	17% 8% 3 5% 5% 3 5% 4 5% 6% 40%	1800
	11th to 20th	Night	19% 5% 2 5% 4 2 4 4 5% 6% 45%	1948
	21st to end	Night	22% 6% 2 4 3 2 3 4 5% 8% 41%	1980
October	1st to 10th	Night	22% 9% 3 6% 6% 3 4 4 5% 6% 33%	1986
	11th to 20th	Night	23% 13% 3 7% 6% 3 4 4 4 5% 27%	2272
	21st to end	Night	27% 15% 3 6% 5% 3 4 5% 4 6% 23%	2574
November	1st to 10th	Night	20% 17% 4 7% 6% 3 4 3 5% 5% 25%	2407
	11th to 20th	Night	18% 16% 6% 10% 7% 2 4 3 4 5% 25%	2470
	21st to end	Night	18% 18% 7% 12% 7% 3 4 3 3 5% 20%	2607
December	1st to 10th	Night	19% 22% 8% 13% 8% 3 5% 3 3 3 12%	2660
	11th to 20th	Night	17% 21% 8% 15% 9% 4 4 3 3 3 13%	3288
	21st to end	Night	22% 17% 7% 13% 8% 3 4 4 3 4 15%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	79% 4 7% 8% 2	1518
	11th to 20th	Day	72% 5% 6% 10% 5% 1	1520
	21st to end	Day	69% 4 8% 12% 7% 1	1592
February	1st to 10th	Day	77% 3 5% 9% 5% 1	1516
	11th to 20th	Day	75% 3 8% 8% 5% 1	1757
	21st to end	Day	69% 4 7% 11% 7% 2	1480
March	1st to 10th	Day	67% 4 8% 12% 6% 3	1800
	11th to 20th	Day	62% 4 10% 11% 11% 2	1872
	21st to end	Day	64% 3 7% 16% 9% 2	2333
April	1st to 10th	Day	64% 4 7% 15% 8% 2	2160
	11th to 20th	Day	55% 4 8% 20% 12% 1	2173
	21st to end	Day	61% 5% 8% 14% 8% 3	2340
May	1st to 10th	Day	57% 4 7% 19% 11% 1	2354
	11th to 20th	Day	55% 5% 9% 19% 11% 1	2482
	21st to end	Day	51% 9% 12% 18% 9% 1	2725
June	1st to 10th	Day	60% 5% 11% 17% 6% 1	2520
	11th to 20th	Day	49% 7% 11% 22% 10% 1	2520
	21st to end	Day	56% 8% 10% 18% 7%	2520
July	1st to 10th	Day	47% 7% 13% 22% 10%	2450
	11th to 20th	Day	49% 9% 12% 24% 6%	2445
	21st to end	Day	52% 8% 12% 21% 6%	2591
August	1st to 10th	Day	50% 9% 16% 21% 5%	2457
	11th to 20th	Day	48% 9% 16% 18% 8%	2304
	21st to end	Day	47% 7% 13% 21% 12%	2394
September	1st to 10th	Day	45% 6% 13% 25% 10% 1	2160
	11th to 20th	Day	44% 5% 10% 27% 14% 1	2012
	21st to end	Day	47% 8% 12% 22% 10% 1	1980
October	1st to 10th	Day	57% 6% 11% 17% 9%	1972
	11th to 20th	Day	56% 7% 14% 17% 6%	1688
	21st to end	Day	68% 4 9% 12% 6% 1	1782
November	1st to 10th	Day	61% 4 11% 16% 8% 1	1671
	11th to 20th	Day	66% 5% 9% 9% 8% 2	1710
	21st to end	Day	68% 6% 11% 11% 3	1572
December	1st to 10th	Day	76% 4 7% 8% 4	1520
	11th to 20th	Day	70% 4 6% 12% 7% 1	1906
	21st to end	Day	76% 5% 5% 10% 4	2772
January	1st to 10th	Night	80% 4 6% 7% 3	2649
	11th to 20th	Night	77% 5% 6% 8% 3 1	2660
	21st to end	Night	72% 4 7% 10% 6% 1	2798
February	1st to 10th	Night	75% 4 6% 9% 5%	2444
	11th to 20th	Night	73% 4 6% 11% 5% 1	2100
	21st to end	Night	68% 4 6% 12% 9% 1	1776
March	1st to 10th	Night	67% 4 7% 14% 7% 2	2160
	11th to 20th	Night	63% 4 8% 13% 10% 2	2088
	21st to end	Night	62% 3 6% 17% 9% 2	2021
April	1st to 10th	Night	63% 5% 8% 14% 10% 1	1800
	11th to 20th	Night	55% 5% 9% 19% 12%	1736
	21st to end	Night	58% 6% 9% 14% 10% 2	1620
May	1st to 10th	Night	56% 5% 8% 17% 13% 1	1620
	11th to 20th	Night	51% 6% 11% 18% 12% 2	1416
	21st to end	Night	50% 8% 12% 20% 10% 1	1551
June	1st to 10th	Night	55% 7% 9% 21% 8%	1440
	11th to 20th	Night	47% 7% 12% 22% 9% 3	1440
	21st to end	Night	53% 8% 13% 19% 7%	1440
July	1st to 10th	Night	44% 10% 13% 22% 11%	1400
	11th to 20th	Night	41% 10% 14% 28% 7%	1392
	21st to end	Night	46% 9% 14% 22% 9%	1486
August	1st to 10th	Night	40% 8% 19% 27% 6%	1438
	11th to 20th	Night	45% 8% 16% 21% 10%	1596
	21st to end	Night	44% 6% 15% 25% 11% 1	1958
September	1st to 10th	Night	45% 6% 14% 25% 10%	1800
	11th to 20th	Night	41% 5% 13% 28% 11% 1	1948
	21st to end	Night	43% 7% 13% 25% 10% 2	1980
October	1st to 10th	Night	53% 5% 10% 21% 11% 1	1986
	11th to 20th	Night	59% 6% 11% 17% 6%	2272
	21st to end	Night	64% 6% 10% 12% 7% 1	2574
November	1st to 10th	Night	62% 5% 10% 15% 8% 1	2407
	11th to 20th	Night	64% 4 8% 15% 7% 2	2470
	21st to end	Night	70% 5% 9% 12% 4	2607
December	1st to 10th	Night	78% 5% 6% 8% 2	2660
	11th to 20th	Night	78% 4 5% 7% 6%	3288
	21st to end	Night	75% 6% 6% 9% 4	4884

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	27% 23% 34% 13% 2	180
	11th to 20th	Day	32% 29% 26% 9% 3 1	180
	21st to end	Day	27% 25% 33% 11% 4 1	178
February	1st to 10th	Day	43% 28% 20% 8%	204
	11th to 20th	Day	32% 30% 27% 9% 2	416
	21st to end	Day	30% 29% 26% 14% 1	346
March	1st to 10th	Day	31% 22% 30% 14% 3	420
	11th to 20th	Day	29% 29% 25% 13% 4	420
	21st to end	Day	34% 20% 24% 15% 6% 1	462
April	1st to 10th	Day	37% 20% 24% 13% 5% 1	420
	11th to 20th	Day	34% 22% 25% 10% 7% 2	412
	21st to end	Day	34% 24% 24% 13% 4 1	420
May	1st to 10th	Day	40% 17% 24% 13% 5% 1	423
	11th to 20th	Day	27% 20% 31% 16% 4 2	447
	21st to end	Day	23% 20% 33% 18% 6% 1	485
June	1st to 10th	Day	34% 15% 30% 14% 6%	450
	11th to 20th	Day	23% 19% 28% 20% 9% 1	450
	21st to end	Day	25% 16% 33% 16% 9% 2	450
July	1st to 10th	Day	21% 12% 31% 25% 9% 1	445
	11th to 20th	Day	18% 12% 36% 23% 8% 2	444
	21st to end	Day	20% 10% 36% 25% 6% 2	488
August	1st to 10th	Day	18% 12% 30% 26% 12% 2	446
	11th to 20th	Day	19% 9% 30% 23% 15% 4	439
	21st to end	Day	25% 15% 23% 21% 12% 4	495
September	1st to 10th	Day	22% 14% 27% 20% 14% 4	450
	11th to 20th	Day	23% 14% 21% 20% 15% 7%	450
	21st to end	Day	19% 17% 24% 23% 12% 5%	450
October	1st to 10th	Day	27% 18% 23% 17% 11% 3	450
	11th to 20th	Day	29% 21% 25% 15% 8% 2	394
	21st to end	Day	36% 23% 22% 13% 5%	396
November	1st to 10th	Day	34% 19% 27% 15% 4 1	365
	11th to 20th	Day	31% 24% 26% 13% 5% 1	370
	21st to end	Day	32% 21% 30% 14% 3	232
December	1st to 10th	Day	32% 24% 27% 12% 6%	180
	11th to 20th	Day	36% 29% 25% 9% 1	180
	21st to end	Day	41% 22% 28% 7% 2	198
January	1st to 10th	Night	28% 26% 29% 15% 3	760
	11th to 20th	Night	25% 27% 29% 15% 3	760
	21st to end	Night	21% 25% 30% 19% 5%	800
February	1st to 10th	Night	25% 26% 29% 18% 3	720
	11th to 20th	Night	24% 25% 32% 15% 3	703
	21st to end	Night	26% 20% 32% 19% 2	592
March	1st to 10th	Night	27% 22% 29% 19% 3	720
	11th to 20th	Night	30% 20% 27% 17% 6%	720
	21st to end	Night	32% 18% 24% 18% 7% 1	792
April	1st to 10th	Night	34% 19% 24% 18% 4	720
	11th to 20th	Night	30% 18% 25% 19% 7%	672
	21st to end	Night	32% 15% 28% 19% 5%	540
May	1st to 10th	Night	30% 13% 29% 21% 6% 1	540
	11th to 20th	Night	23% 12% 33% 24% 7% 1	354
	21st to end	Night	22% 11% 26% 32% 7% 1	389
June	1st to 10th	Night	31% 8% 25% 26% 9% 1	360
	11th to 20th	Night	20% 9% 25% 34% 12%	360
	21st to end	Night	19% 8% 29% 35% 10%	360
July	1st to 10th	Night	17% 6% 29% 34% 13% 1	350
	11th to 20th	Night	14% 5% 28% 35% 16% 1	348
	21st to end	Night	15% 6% 25% 38% 16%	394
August	1st to 10th	Night	19% 4 17% 40% 19% 1	374
	11th to 20th	Night	18% 7% 22% 34% 18% 1	532
	21st to end	Night	20% 6% 24% 32% 16% 2	770
September	1st to 10th	Night	20% 8% 26% 32% 14% 1	720
	11th to 20th	Night	22% 8% 20% 29% 18% 3	720
	21st to end	Night	24% 11% 25% 24% 14% 2	720
October	1st to 10th	Night	29% 12% 23% 23% 13% 1	720
	11th to 20th	Night	31% 16% 23% 20% 8% 2	720
	21st to end	Night	35% 17% 26% 18% 4	792
November	1st to 10th	Night	33% 15% 29% 17% 5%	740
	11th to 20th	Night	27% 21% 28% 15% 7% 1	760
	21st to end	Night	29% 24% 26% 15% 5% 1	760
December	1st to 10th	Night	33% 25% 26% 13% 3	760
	11th to 20th	Night	31% 24% 27% 14% 4	760
	21st to end	Night	33% 23% 26% 15% 2	836

Page generated at 2024-01-19 09:28:33. Version ac07

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